Expulsive choroidal hemorrhage is one of the most devastating complications that can occur during intraocular surgery. Permanent and frequently total vision loss in the involved eye is the common result. Damage occurs when leakage from a choroidal blood vessel elevates the uvea off its scleral bed resulting in the expulsion of intraocular tissues, including the retina through the surgical incision. The hemorrhage or fluid leakage is thought to result from a change in the trans-vascular pressure gradient due to the globe being surgically opened and depressurized. This complication occurs at a rate of approximately 1 in 10,000 cataract operations and 1 in 1,000 penetrating kepatoplasties, resulting in the loss of approximately 200 eyes per year in the United States.
The only known methods for controlling a choroidal hemorrhage are to reseal the eyeball or emergency surgical drainage of suprachoroidal hemorrhage. Closing the surgical incision prevents the expulsion of ocular contents and allows the intraocular pressure to rise to a level such that further bleeding is stopped. Surgical closure of a cataract incision or penetrating keratoplasty opening with sutures takes at least several minutes and frequently cannot be accomplished before important intraocular structures have been extruded through the wound. At this time, the suggested method for rapidly closing the globe is the placement of the surgeon's gloved finger over the cornea or graft opening and the application of pressure until the bleeding stops.
Several disadvantages of this method are evident. Sealing the wound with a finger may be difficult or impossible. Excessive pressure in the absence of an adequate seal may itself cause expulsion of intraocular contents. Excessive elevation of intraocular pressure due to digital compression above that required to seal the wound may cause permanent damage due to interruption of ocular blood flow. A good deal of guesswork is involved in determining whether the bleeding has stopped and when it is safe to remove the finger. Releasing the pressure can stimulate further bleeding and allow intraocular tissues to prolapse through the wound. If the bleeding has not stopped at the time the finger is removed, the finger must be reinserted and more pressure applied, thereby increasing the chance of additional damage to the cornea.
Pressure on the anterior corneal surface by the surgeon's finger everts the cornea and presses its delicate inner lining (endothelium) against the iris, lens and intraocular tissues. The thin layer of cells lining the cornea are responsible for keeping the cornea clear. These cells are extremely susceptible to damage and are irreplaceable. The distortion of the cornea and contact with other structures required to control an expulsive hemorrhage usually causes sufficient damage to cause permanent clouding of the cornea. If the eye is salvaged, corneal transplant surgery is usually required to restore a clear front surface to the eye.
Another disadvantage of using digital pressure to seal the anterior segment is that the surgeon's finger obstructs the view into the eye. This makes it difficult or impossible to monitor the progress of the hemorrhage.
Because of visualization problems and distortion of the normal anatomical position of the wound margins, it is not possible to suture the wound while digital pressure is maintained. When the surgeon's finger is removed, either to look into the eye or to attempt suturing, the pressure is decreased, stimulating further bleeding and allowing intraocular tissues to prolapse.
The iris, ciliary body, and retina are delicate intraocular tissues that if extruded from the eye are usually irreversibly damaged. If the retina is extruded from the eye, permanent blindness of that eye almost certainly results.